Used gum stuck on a wall is just nasty! Except if it’s a huge collection of thoughtfully place bubble gum. Like Gum Wall, Post Alley, Seattle, for example. The practice of sticking used gum on the wall started back in the 90's while patrons waiting in line to buy theater tickets. Attempts were waged to clean up the sticky situation, but to no avail. People kept depositing their spent gum on the wall. It’s now become a tourist attraction. For more images, check out Cooked Brains.
Photo credit, Wallstreetfighter.